Physiological changes in pregnancy

Mr Manas Chakrabarti September 2011

∗ To provide a suitable environment for the growth and development of the fetus.

∗ In part, to meet the metabolic demand brought on by the fetus. placenta and uterus

∗ In part, due to the progesterone and oestrogen

∗ Progesterone remains increased throughout pregnancy (corpus luteum > placenta) ∗ Smooth muscle relaxation ∗ Raises body temperature

Endocrine changes

∗ Increased oestrogen ∗ Breast, nipple growth ∗ uterine blood flow, myometrial growth ∗ Cervical softening ∗ oxytocin receptors ∗ water retention ∗ TBG

Endocrine changes

∗ Human placental lactogen (promotes growth) ∗ insulin secretion but

∗ insulin's peripheral effect (fatty acids and glucose

diverted to the fetus)

Endocrine changes

∗ The pituitary gland (enlarges in size) ∗ Prolactin es (secondary to oestrogen stimulation) ∗ ACTH but LH, FSH ∗ Cortisone output but the free levels normal ∗ oxytocin first stage of labour and suckling

Endocrine changes

∗ Effect of pregnancy on the thyroid ∗ enlarges (due to demand in pregnancy) ∗ relative iodide deficiency (renal clearance) ∗ Thyroid-binding globulin (TBG) is doubled (oestrogen)

∗ Total T3 and T4 rise but then normalises ∗ TSH may decrease but then normalises

Endocrine changes

∗ Plasma volume ∗ Increases from 6 weeks ∗ Rapid expansion 30-34 weeks ∗ Up to 50% (extra 1500 mL)

Haemodynamic changes

∗ Red cell mass ∗ 20% ∗ Physiological anaemia

(dilutional effect, second trimester)

∗ Mean corpuscular haemoglobin concentration: constant.

Haemodynamic changes

∗ White cell count ∗ Neutrophilia peaks at 32 weeks ∗ Massive neutrophilia : during labour. ∗ lymphocyte function and cell-mediated immunity ∗ Eosinophils almost absent in delivery

Haemodynamic changes

∗ Platelets slightly ∗ Clotting factors , Fibrinogen

∗ Pregnancy hypercoagulable state

Haemodynamic changes

∗ Cardiac output from 5 to 6.5 L/min ∗ Stroke vol by 10% ∗ pulse rate 15 beats/m1n ∗ Delivery output further increases

Cardiovascular changes

∗ Peripheral resistance by 50% ∗ BP in second trimester then to pre-pregnancy

level ∗ Uterine compression : supine hypotension syndrome ∗ Renin-angiotensin system plays a critical part

Cardiovascular changes BP

∗ Tidal volume by 40% (progesterone effect) ∗ Resting pregnant woman ventilation by breathing

more deeply and not more frequently. ∗ Breathlessness common as pCO2mat is set lower to

breath out fetal CO2

Respiratory system changes

∗ 10 fold in weight and blood flow ∗ Cavity enlarges 1000 fold ∗ Muscle hypertrophy till 20wk the stretching ∗ Massive hypertrophy of uterine and ovarian vessels

Changes in uterus

∗ Reduction in cervical collagen (softens) ∗ Hypertrophy of cervical glands (discharge) ∗ Thick mucous plug : protective

Changes in cervix

∗ Venous congestion bluish tint ∗ High oestrogen levels stimulate glycogen more

lactic acid, protective

Changes in vagina

∗ Lactiferous ducts and alveoli develop (oestrogen, progesterone, prolactin)

∗ Colostrum is formed as early as 12 weeks ∗ Lactation ∗ Sudden withdrawal of E+P prolactin starts lactation ∗ Suckling oxytocin milk ejection

Changes in breast

∗ Renal blood flow increases 50% ∗ GFR, several blood level decreases

∗ Kidney size , dilatation of calyces and ureter ∗ Detrusor relaxation ∗ vesicoureteric reflexes

Changes in urinary tract

∗ Smooth muscle relaxation (progesterone) heartburn constipation problems in digestion

Changes in alimentary system

∗ Pigmentation in linear nigra, areola, chloasma ∗ Palmar erythema ∗ Striae (stretch marks)

Changes in skin

Changes in life…

Thank you